I can tell that you are anti US as your opinions are heavily weighted in that way.
Everyone in the developed world thinks it's common sense to restrict access to firearms. Not the USA - That's Theft of Freedom.
The problem with removal of guns is that our country was built on this freedom. There are many very good reasons for gun ownership, one being wild animals. much of Europe does not have large carnivores (bears, wolves, etc) like the US does.
If people want to change this, there has to be a major change, such as a constitutional amendment. This is not something you can just decide to change. You would have to convince some percentage of states to agree to an amendment (I can't remember my high school civics well enough for the %, but it is easily looked up and I am too lazy at this moment).
These are some of the problems with starting from the point of view of just removing guns, it isn't that easy. Mostly though, the issues with guns in the US are nothing to do with the guns themselves which are tools, but with the situation of mental health in the US. If mental health care was easier to get, and there wasn't this massive stigma of it, there would be less people out there with these untreated issues.
Now, saying we should get rid of the guns in the US, doesn't solve the problems of violence, just removes the average citizen's ability to defend themselves against violence, which causes such things as happened recently in a Sydney cafe, and at a newspaper in Paris. Even the police were ill equipped to deal with a determined terrorist. If the police were armed, or even some of the citizens in these cases, less harm would have been done to these people.